The Untitled JJ Abrams project,
ultimately a SF movie now codenamed Cloverfield (debuts Jan 8, 2008), has a
puzzle site of sorts, ethanhaaswasright.com.
So far, the puzzles are attractive but tedious. A trailer is in front of the
Transformers movie, I've heard.

Would you like to make a challenging maze with many vortices? The paper by
Jie Xu and Craig S. Kaplan, Vortex
Maze Construction, gives an excellent overview of the problem, lots of
insight, and lots of mazes.

The Angel Wins

On an infinite 2D board, a chess piece called the Angel can move up to n spaces
each term. A piece called the Devil destroys one square each turn. If the Devil
can surround the Angel with destroyed squares, the Devil wins. Who wins? in
a recent paper, Peter Gacs argues that The
Angel Wins.

Alice is Lost

Eric Harshbarger has made an online puzzle series called Alice
is Lost, which
has an Alice in Wonderland motif.

Bloxorz is a fairly nice flash game with rolling block mazes, as championed
by Robert Abbott of logicmazes.com.

Walking and Hopping Toys

Can an object walk down a mild ramp with no gears or batteries? peter Steinkamp
shows many varieties of what he calls Unpowered
Walkers and Hoppers.

3 Million Visitors

Dick Saunders Jr.: What date will you turn over 3 Million Visitors? I will
guess July 4, 2007. [Ed - Hmmm... about 2969000 right now. Apologies for the
length of the break. In 1991 I
bought a house in Colorado for $17,777.77. Now on 7/7/7, I've closed on it
(for more), and moved most of the things in it to my home here in Champaign
IL. So I've done lots of packing, unpacking, cleaning, and truck driving. My
mom was living in the Colorado house, and now doing comfortably in an assisted
living facility.]

Nick Baxter: The Google U.S. Puzzle
Championship is coming up next weekend--June
16. Winner gets a trip to Rio de Janeiro with the U.S. Puzzle Team. Anyone
can enter -- but they must enter by June 14th (Thursday). [Ed - Anyone entering
can expect to find many top-notch puzzles.]

Rubik's Cube in 26 Moves

Northeastern University computer science professor Gene Cooperman and graduate
student Dan Kunkle have proven that any
configuration of a Rubik's cube can be solved in 26 moves.
The research from Cooperman and Kunkle improves upon the previous record by
one move. The use of 7 TB of distributed disk as an extension to RAM for holding
large tables and the development of faster computer moves using mathematical
group theory were keys to their research efforts. For more details, see the
paper, "Twenty-Six
Moves Suffice for Rubik’s Cube."

Material added 29 May 2007

Public Service Award from National Science Board

Numb3rs received a public
service award from the National Science Board,
so I went to Washington DC (see the full story at the Wolfram
Blog). Here's a picture from the diplomatic reception room at the State
Department. From left to right, Michael Trott (Mathematica
Guidebooks), Ed
Pegg Jr (mathpuzzle), Cheryl Heuton (Numb3rs series creator), Eric Weisstein
(MathWorld), and Amy Young. If you'd like to hear my voice, I did a radio interview
with Amy Young on NPR's
Afternoon Magazine.

DROD: The City Beneath

If you like puzzles, you need to try DROD:
The City Beneath. I found the predecessor, Journey
to Rooted Hold, to
be the best game I ever played. Now that I'm deep, deep into TCB (specifically,
the Holding Vats), I have a new all-time favorite game. Truly a superb game
(if you like thinking).

RSA Factoring Challenge Discontinued

Dick Saunders Jr.: At RSA
Labs is the message "This challenge is no longer active." I
suppose that will make the Cunningham
Project the primary place for factoring
challenges.

Turing Challenge Announced ($25,000)

Is there a universal 2,3 Turing machine? A resolution of the question either
way will net you $25,000 from Stephen Wolfram, in the first Wolfram
Research Prize.

Kurchan Squares Contest Results

In a Kurchan square,
numbers 1 to n2 are arranged in a grid, and the difference
between the maximal and minimal product is made as small as possible. The
best known Kurchan squares have
been greatly increased in the latest Al Zimmermann contest.

Crossword Compiler 8

If you'd like some assistance in making crosswords, Crossword
Complier 8 is the best program on the market. The various puzzles I've had in the
New York Times were made with the assistance of earlier versions of Crossword
Compiler.

The Game of Life exploration tool Golly
1.2 has been released. It features fast updates, huge universes, and
a large library of examples.

Bill Clinton's NYT Crossword

On May 6, the Games and Puzzles section of the New York Times, under the
guidance of Will Shortz, will be in a new, revamped format. The first crossword
featured in this new section will be by crossword aficionado Bill Clinton,
who was seen as a solver in the movie Wordplay.
And here's the crossword: Twistin'
the Oldies.

A Great Issue of Games Magazine

Lots of good game and puzzle magazine have folded lately. At the same time,
Games Magazine has really
been putting out a string of great issues. It starts with an Andrea
Gilbert maze cover, and contains a Gottlieb-Selinker-Woodruff puzzle extravaganza,
an incredible meandering crossword by Frank Longo, an article by Tom Cutrofello
about puzzle designer Michael Toulouzas,
and the usual collection of great puzzles.

Polyomino Magic Squares

Erich Friedman latest Math
Magic ponders how multiple copies of a polyomino
can be placed in a square so that every row and column has the same number
of filled squares.

Alexandre Owen Muniz: On May 15, the US Postal Service is increasing the
cost of a first class stamp to 41 cents. Here's something else you can do with
41 pennies. Two connected arrangements of coins are the same polycoin if you
can transform one to the other by sliding coins without changing which coins
are adjacent, or by a combination of flipping the arrangement and coin sliding.
There are 13 pentacoins. I've found a 41
coin arrangement with the property
that all of the pentacoins are contained within it, and if any coin is removed
this
ceases to be true. I believe that no larger arrangement
with this property is possible.

Nicholas Quaine: The G3ode
puzzle is
a polyhedron with tiles covering all facets but one. Each tile has two distinctively
coloured sides. Any of the 3 tiles adjacent to the empty facet can be flipped
into that space. The puzzle is solved when all tiles are flipped such that
the surface of the puzzle is all one colour. G3ODE is copyrighted freeware,
currently available for the Windows XP operating system.
Angel

From nsf.gov:
The popular television drama series "Numb3rs," about an FBI agent whose brother,
a genius mathematician, helps solve crimes in the Los Angeles area by using
mathematical problem-solving techniques, will receive a National Science Board
group Public Service Award for 2007, along with the program's co-creators,
Nick Falacci and Cheryl Heuton.

The CBS Paramount-produced drama and its two collaborators will be honored
for their contributions toward increasing scientific and mathematical literacy
on a broad scale at a ceremony May 14 at the State Department in Washington,
D.C. [Ed - so I'll be in Washington on May 14.]

"Numb3rs" is the first television series on
which Falacci and Heuton have collaborated. Wisely bringing in several mathematicians
as consultants, the producers were able to provide realism to the mathematical
theories employed in the crime-solving cases of each episode. Experts say that
the various theories and mathematical problems and equations used on the program
are easily transferable to equivalent real-world situations. Cryptanalysis,
probability theory, game theory, decision theory, principal components analysis,
multivariate time series analysis and astrophysics are just some of the many
disciplines employed in the series thus far. Working mathematicians of the
Mathematical Association of America have recognized the accuracy and validity
of the theories and their presentations on the program.

Bill Clinton to write NYT Crossword

On May 6, the Games and Puzzles section of the New York Times, under the
guidance of Will Shortz, will be in a new, revamped format. The first crossword
featured in this new section will be by crossword aficionado Bill Clinton,
who was seen as a solver in the movie Wordplay.

Christian Boyer: The April 2007 update of www.multimagie.com
is online. You will see a new page on the first bimagic square of primes, but
also some other news.

Hexagonal Spirallohedra

Russell Towle has made a great series of youtube videos about zonohedra.
One of them is his video on Hexagonal
Spirallohedra.

Logical Labyrinth

Eric Harshbarger had a puzzle
party for his birthday. The A to Z puzzle is interesting -- what's the
optimal list? The Logical
Labyrinth is quite impressive.

Burrtools, Winedt, Great Stella

Various useful programs: BurrTools,
for studying burr puzzles, has a new update. WinEdt
5.5, one of the best LaTeX
editors on Windows, has just been released as a new version. Stella
4D was
released with a price drop. There is no more comprehensive database of polyhedra
that I know of -- I've found it a useful tool so far.

A few years ago I wrote
a column about a great puzzle game. I finished
it with "The game is huge, clever, well paced, and entertaining. I agree
with the high praise that DROD:
Journey to Rooted Hold has gotten so far
-- this is the best puzzle game of all time." The game was received
well for an independent game, and two years later, the sequel, DROD:
The City Beneath, is now available. A PC
demo, Mac
demo, and Linux
demo are all available. This sequel is a great continuation of DROD:
JtRH. Highly recommended.

The Big Dig Litigation Graph

Joseph DeVincentis: What gets the Boston Globe to print (almost) the complete
graph on 15 nodes the front
page of its local section? A story about the lawsuits filed as a result
of the tunnel ceiling collapse last year. The main story is The
Big Tangle. [Each line represents two people suing each other.]

MayDay Mystery

Aaron Enright: Since the 1970's, strange notices have been printed on May
Day. I must say that I'm intrigued
by this webpage about the MayDay
Mystery. Even if it's utter nonsense, I admire nonsense that can go on
for this long.

11111 .... 111111 is prime!

Harvey Dubner: On March 28 I found a new probable prime repunit, R(109297),
which consists of 109297 1's. It is effectively impossible to prove true primality
at this time. The only known repunit primes are R(2), R(19), R(23), R(317),
and R(1031). In 1999 I found the PRP repunit R(49081), and in 2000 Lew Baxter
found the PRP repunit R(86453).

Material added 1 April 2007

Abel Prize for Srinivasa S. R. Varadhan

S.R. Varadhan has won the 2007 Abel
Prize, "for his fundamental contributions
to probability theory and in particular for creating a unified theory of large
deviation."

Bob Abbott on Mazes in Numb3rs

Robert Abbott: I finally finished writing my
discussion of the episode of NUMB3RS that was about logic mazes. The
writing took longer than I thought, probably because I was conflicted about
whether to support the show or complain about it. I ended up complaining
too much.

Tobias Kreisel and Sascha Kurz have found a set of points, no three on a
line and no four on a circle, so that all points are at integer distances from
each other. It's an Integer
Distance Heptagon. The existance of an integer heptagon has been a long-unsolved
question. Is there an integer octagon?

Open Office 2.2 and Burrtools

I use Open Office, a spreadsheet - word processing - drawing program, all
the time. They just came out with version 2.2. While I'm at it, Burrtools has
another update.

Jeff Montanye: You may be interested in my site: www.mazezing.com.
[Very nice photographs of maze sculptures.

Puzzle Museum Curator

If you know puzzles really well, you can apply to be a curator. The Lilly
Library at Indiana University, Bloomington, Indiana has just begun a search
for a full time Curator
of Puzzles to supervise the Slocum Puzzle Collection,
which is being donated to the Library. The Slocum Room, which will house and
display the puzzles, was opened August 2, 2006 and has a permanent display
of the first group of about 500 puzzles. The remaining 29,500 puzzles, 5000
books and all the Slocum files will be donated to the Library over the next
few years.

Lobster Point

George Sicherman: Rotary on a vertex is harder than it looks! (In other words,
making a rotational
oddity that works on a vertex is more difficult that the
less constrained problem.)

Michael Trott's Quantum Views

Bohm's Quantum Mechanics may sound like a dry subject, but Michael Trott
knows how to make almost any science topic beautiful. Apple.com wrote about
him in their article Quantum
Views.

Material added 21 Mar 2007

synchroplastikum

I'm fascinated by what tiny programs can do. My new favorite is a 4K program
called synchroplastikum,
by calodox.
It unspools into an intricate 1 minute movie with kick-ass music. The 19K image
below does not do justice.

Puzzler Scott Weiss make Jeopardy history

The first 3-way
tie in Jeopardy history occurred recently. A frequent maker
of puzzle extravaganzas, Scott Weiss (National
Puzzler League member Squonk)
decided to be nice to both of his opponents. In game theoretic terms, he
already knew he could beat them, so he had a choice between two known opponents,
or two unknown opponents. More is mentioned at Heaneyland.
A video of the closing event is at Youtube.This
weekend, he'll be at the American
Crossword Tournament, hosted by Will Shortz

Kakuro article by Will Shortz

In his NYT article "A
Rush of Excitement", Will Shortz shows his puzzle historian
chops by tracking down the first publication of Kakuro. "Invented by a Canadian
building constructor, James E. Funk, it was first published in the United States
in 1950 in Official Crossword Puzzles magazine under the name “cross
sums.” Gradually, cross sums grew in popularity and became a regular
feature in Dell puzzle publications. The publisher Nikoli picked it up in the
1980s, renamed it and spurred its international growth."

Nikoli article by Martin Fackler

In another NYT article, "Inside
Japan's Puzzle Palace," the history of Nikoli is discussed. Virtually all of the current puzzle crazes were initially invented
of nurtured by Nikoli, the leading publisher of puzzles in Japan.

Japan Puzzlers Article by Mariko Yasumoto

One of the reasons puzzles are so popular in Japan right now is their strong
link to brain health. If you solve a puzzle every day, your brain will be much
healthier. The Washington Post article "Aging
Japanese Keep Their Minds Moving"
discusses more of the research behind heightened puzzle popularity.

Lie Algebra E8

An MIT announcement claimed
the calculation of a character table for Lie algebra E8. More information is
at aimath.org. To do this, they computed
Kazhdan-Lusztig-Vogan polynomials for the split real form
of E8, which has 453,060 irreducible representations.

Crossing Number 7

I'm preparing an article about crossing numbers in cubic graphs.The first
graph below is the Desargues
graph, which has crossing number 6. If you look
closely, you'll see that the edges cross over each other in six places. I found
this particular embedding, and it looks really nice. Graphs
2-6 are smallest graphs with crossing number 7, found by Geoff Exoo. These
embeddings here look
terrible. Can anyone find really nice embeddings? Some of
the programs you can use to move points around are Compass
and Ruler, Geogebra,
Geonext, Openeuclide,
and jgraphed. It wouldn't surprise
me at all if a 10-year old found an unbeatable embedding, and that became the
standard. Send
embeddings.

Hexa-Trex

Bogusia Gierus: I developed a new math puzzle called Hexa-Trex. The object
of the puzzle is to find a path through ALL the tiles to make a math equation.
A tile can be used more than once, but no immediate backtracking is allowed
. Two or three digit numbers can be made from individual digits. This simple
concept makes for a challenging at times puzzle. I try to post a new puzzle
each day on my website.

Material added 10 Mar 2007

The Crosshatch Puzzle

Richard Saunders, Jr.: I wanted to suggest a puzzle to you of my own. You
need 16 squares of paper: 9-single diagonal (corner to corner), 3-two diagonals
(intersecting, both corner to corner), 4-blank. Make one big square with five
lines. Send Answer.

For more 2-dimensional fare, clips and trailers from Flatland:
The Movie are available. Martin Sheen (West Wing), Kristen
Bell (Veronica Mars), Tony Hale (Arrested Development),
supply the some of the voices.

Tilings w/o Corners

Erich Friedman: Many cool tilings at the Math
Magic page. Reid, Hamlyn,
and Sicherman obviously have better tiling programs than I do.

Terrence Tao: Some personal thoughts and opinions on what "good
quality mathematics" is, and whether one should try to define this term rigorously.
As a case study, the story of Szemeredi's theorem is presented.

Oskar's Triangular wins Mobile Games award

Oskar van Deventer's Triangular game
has won the top honors in the IMGA
awards. Triangler is a massive collaborative geometric outdoor mobile interactive
game. Two teams of 100 players play a two-hour match in a city or rural area.
The object of the game is to enclose enemy players with 2000-meter equilateral
triangles formed by you and your team buddies. [As a side question -- 7 people
can make 6 unit triangles. 12 people can make 12 unit triangles. Are there
solutions to most unit triangles with n points?]

Hexahex Cell Shifts

George Sicherman: I've put up some Hexahex
Cell Shifts. I'm pretty sure
that the last 2r3 can be improved, but no luck so far!

Andrew Clarke: This one's quite a lot harder by hand. If we combine a 2x2
square, a domino and a single square we get a set of 21 pieces. The attached
is based on one solution to a 7x21 rectangle. [Andrew also found a 10-clue
puzzle based on a complete set.]

Laszlo Kozma: Here's a simple game that I thought of, I never heared of
it anywhere, but probably it is too simple not to have been invented already.
If it exists already, and has a name, I'd be happy to learn about it. Two-player
game, played on mxn rectangular checkered board, players alternate in putting
a piece in a free square (just like in go). It is not allowed to put a piece
in a square that has any of it's neighbours (out of the 8 (or 5 if on the margin))
occupied. If a player can't put a piece anywhere, he loses... I'd be interested
to find out who has a winning strategy if anyone. For smaller boards it's trivial
of course, but for larger boards it seems too much computation is needed to
find a strategy. Puzzle: Who wins 4x4, 4x5, 4x6, 5x6, and 6x6? Send
Answer.

Chessboard Attacks

Erich Friedman: Arrange 4 white knights and 4 black knights so that each
knight attacks 3 pieces of the other color. This and many similar problems
are at the latest Math
Magic. If you can extend or improve any of these solutions,
send them in to Erich.

M&M's Dark Puzzle

An interesting corporate puzzle has been used to promote M&M
Dark. 50 movies are hidden in a spooky picture.

From puzzles.com: The members of the
2007 US Sudoku Team have been announced: Grayson Holmes, Wei-Hwa Huang, Jonathan
Rivet, Jim Schneider, Thomas Snyder, and Jason Zuffranieri. From puzzler.co.uk:
Are you Britain's best Sudokulist? We're looking for team members for the World
Sudoku Championship in Prague in late March, and the qualifying
competition is being held on 8-10 February.

New Amazing Tilings

Joseph S. Myers: I've now added results on polymorphic
tiles, including three new 10-morphic tiles and an 11-morphic tile.

Christian Boyer: I've updated my Taxicab
and Cabtaxi page. Because several persons
ask me the intermediate values, the .TXT files with the full list of the upper
bound values and their decompositions in sums (or differences) of two cubes
are now downloadable at the end.

Material added 21 January 2007

Double-6 Sudoku

Andrew Clarke (Poly Pages):
If we add two monominoes to a 2x2 square then we get a one-sided set with 12
pieces which can form a 6x12 rectangle. These can be made into sudoku puzzles.
There is a fair amount of crossover between the two halves and they make reasonably
tricky manual problems. Here's one example with only 11 clues and, surprisingly,
half the peices have no clue in them. I have done this by hand - tricky but
possible.

Eric Vautier: I didn't believe it when I saw something in the output file...
but it was true : 2003663613*2^195000-1 is prime! 2003663613*2^195000+1 is
prime! [An official announcement is at twinprimeresearch.org, there is also
a slashdot
discussion, and a mersenneforum.org discussion.]

Largest Prime Progression found

On Jan 18, 2007, Jaroslaw Wroblewski, with help with the network at the Mathematical
Institute of Wroclaw, became the first person to find an AP24. For k from
0 to 23, 468395662504823 + 45872132836530k is a prime number. The
Prime Arithmetic Progression site
by Jens Kruse Andersen has more information.

Get Off the Earth

A gorgeous rendition of the classic Get Off the Earth puzzle has been printed
by samuelloyd.com.

The Homicidal Chauffer Problem

A mainstay of TV and movies, a car (high speed, low manueverabilty),
tries to run over a pedestrian (low speed, high manueverability. Can the pedestrian
survive? This turns out to be the Homicidal Chauffer problem. There is a history
(ppt) of
the problem available.

Tough Puzzles Magazine Discontinued

Nick Deller: Tough Puzzles has suffered a slump in sales over recent months,
so much so that we've been making a significant loss on every issue. As a result,
Puzzler Media took the hard but, I think, correct decision last week that the
magazine is to cease production with immediate effect. The recently published
Issue 263 will be the last one to reach the printed page. I'll be working on
some brand new titles for a while - probably nothing that will especially tickle
the tastebuds of the Tough aficionados, but I think after 30 months and 10
issues of Tough I've probably earned a bit of time working with the more straightforward
stuff! It's a completely different challenge personally, and one that I'm looking
forward to getting my teeth into.

The 2nd World Sudoku Championship will be held in Prague, Czech Republic,
between March 28 and April 1, 2007. The US Team looks to be very strong this
year, including Thomas Snyder and Wei-Hwa Huang, who placed second and third
respectively in last year's WSC. If you are a US citizen and interested in
joining the US Team, then go to the registration
page for more information, practice, and the qualifying
test. Entries must be submitted by January 15.
[Lots of good Sudoku puzzles there.]

Happy 2007

Erich Friedman: Q: Using the digits 3, 4, 5, 6, 7 each once, and the usual
+ - * / ^ ( ) and concatenation, make the new year 2007. There are 2 solutions.
Hover for Answers.

Geocaching Puzzles

Chris Lusby Taylor: Have you come across Geocaching? It's a leisure activity
that uses GPS receivers to locate caches that people have hidden for this purpose.
When you find a cache you write an entry in its log book and later do the same
on a Web site. Many caches exist simply to challenge you to find a small container
in the middle of, say, a large wood. The precise latitude and longitude will
be clearly stated on the geocaching Web site www.geocaching.com. But a few
involve solving puzzles to get the coordinates. Some of these may be of interest
to you.

Under my alter ego of Mr Tumnus, I have created a number of puzzle caches,
one involving a modified
Sudoku (
) where the latitude and longitude were hidden in the grid, and another a puzzle
of the "Who
owns the zebra" style. This one has proved rather tricky
to solve. To extract the purely mathematical from this puzzle, and distill
it further, try this:

The only cities in Pentland are, from North to South, Naples, Otranto,
Pisa, Rome and Sienna. All are on different longitudes and each has a direct
road to the other four. A new salesman set off from home four weeks ago.
He works Monday to Friday in a different city each day, travelling in the
evenings. On Monday evenings he has always travelled eastwards (that's
not due east, but definitely easterly as opposed to westerly). Similarly
on Tuesday he's gone northwards, on Wednesday westwards and finally on
Thursday southwards. He doesn't travel any more until the next Monday evening.
By now, he's driven all ten roads that link the five cities.
It is Monday. He's spent each of the last four weekends in a different
city, miles from home. Where is home?

Cake Cutting, part 2

Last week, we saw that a 6x6 cake with corner missing could be divided into
7 equal pieces with 3 cuts. Below, a 10x10 cake with a corner missing is divided
into 11 pieces with 4 cuts (solution by Chris Lusby Taylor, also solved by
Warren Phillips). Can you do it with a 9x9 cake with 4 corners missing? Serhiy
Grabarchuk was the first solver of this problem. None of the cuts cross themselves,
and each crosses the other cuts exactly once.

Happy 2007

Marek Penszko: Happy 2 + 7 + 27 + 72 + 207 + 270 + 702 + 720.

Pi and e on a blind date

Lyman Hurd: "Just in case you've wanted an icosahedral pecan pie," Now
where else would I ever find a website with a lead in like that :-). The world
clearly divides into those of us who think this is a cool idea and those other
people! I meant to pass this link along. My daughter forwarded it to me...
Pi and e on a blind
date. Happy New Year. By the way, I got the Gordian Knot puzzle for Christmas
based on your recommendation and my daughter and I have both been enjoying
playing with it.

Spreadsheet competition

Dave Millar: I'm holding a competition to create the best page design and
maze generator in a spreadsheet application. There are many methods of doing
this and they all have varying results. Maybe you can enter and come up with
a new one! Details can be found at The
Griddle or specifically at Maze
Contest. The deadline is January 31st. I hope you all will give it a try!

Mathophobia Leads to Stabbing

Chicago Sun-Times: A 51-year-old Malcolm X College instructor who was demonstrating
a math problem on her blackboard Tuesday was stabbed in the back by a student
who apparently became frustrated with the exercise, authorities said. Full
Story.

Material added 2 January 2007

Oskar's Nutcase

A limited edition Hamayana Cast puzzle by Oskar van Deventer is available
- Cast Nutcase (puzzlemaster.ca).
Oskar has also recently won
an award for his 100-player team game Triangler, where you and two teammates
capture as many opponents as possible in a triangle.

Daedalus Maze Program on Numb3rs

The excellent maze program Daedalus was
recently featured
on Numb3rs. Walter Pullen,the programmer, did a great write-up of his network
debut.

Cake Cutting

A cake with a corner missing can be cut into 7 unequally sized pieces
with 3 cuts, following the gridlines. None of the cuts cross themselves, and
each crosses the other cuts exactly once. Following these rules, cut the cake
into 7 equally sized pieces with 3 cuts. Answers
and Solvers. There are two solutions, so try to solve it before looking
at the solution. Will Shortz mentioned "Beautiful puzzle. I've never seen anything
like it before."

Serhiy Grabarchuk: We wish you a Nice Holiday Season and a Happy and Peaceful
New Year! Attached please find my Holiday Puzzle Greetings. Happy Puzzling!

Square+Two Dominoes Sudoku

Andrew Clarke has been working on a sudoku puzzle based on the 40 shapes
obtainable with a square and 2 dominoes.

BBC MindGames

For Christmas, I got a copy of BBC
MindGames Magazine. It's excellent. Currently, it's tricky to subscribe
to -- I got it only by giving myself a gift subscription, then listing a
fake UK billing address. After that, I could finally put in my credit card
info. It's a lot of hoops, and the subscription website shouldn't be so broken,
but the magazine is top-notch.

Using 1-9

Erich Friedman: What is the only positive integer n with the property that
together 4n and 5n use each digit 1-9 exactly once? Too easy to solve with
a computer, so try to solve it by hand!

Happy 2007 puzzle

2007 is divisible by 9. If a 1 is added onto the end, for 20071, the number
is prime. What can be added to the end of 20071, to obtain another prime? What
delights can be found beyond? Send Answer.

Piano-hinged dissections

Greg Frederickson: I am excited to announce the publication of my new book, "Piano-Hinged
Dissections: Time to Fold!", published by the firm of A K Peters. The
book explores geometric dissections in which the pieces are connected by long,
narrow hinges that run along shared edges---like the hinge on a grand piano
which connects the lid to the sound box. Such hinges allow a type of folding
motion similar to that of origami, the art of paper folding.

Site Goals

Martin Gardner celebrates math
puzzles and
Mathematical Recreations. This site aims to do the same. If you've made
a good, new math puzzle, send it to ed@mathpuzzle.com.
My mail address is Ed Pegg Jr, 1607 Park Haven, Champaign, IL 61820.
You can join my moderated recreational mathematics email list at http://groups.yahoo.com/group/mathpuzzle/.

All material on this site is copyright
1998-2007 by Ed Pegg Jr. Copyrights
of submitted materials stays with the contributor and is used with
permission.